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runtime: treat CTRL_CLOSE_EVENT, CTRL_LOGOFF_EVENT, CTRL_SHUTDOWN_EVE…
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…NT as SIGTERM on Windows

This matches the existing behavior of treating CTRL_C_EVENT, CTRL_BREAK_EVENT as a synthesized SIGINT event.

See https://docs.microsoft.com/en-us/windows/console/handlerroutine for a good documentation source upstream to confirm these values.

As for the usage of these events, the "Timeouts" section of that upstream documentation is important to note, especially the limited window in which to do any cleanup before the program will be forcibly killed (defaults typically 5s, but as low as 500ms, and in many cases configurable system-wide).

These events are especially relevant for Windows containers, where these events (particularly `CTRL_SHUTDOWN_EVENT`) are one of the only ways containers can "gracefully" shut down (moby/moby#25982 (comment)).

This was verified by making a simple `main()` which implements the same code as in `ExampleNotify_allSignals` but in a `for` loop, building a `main.exe`, running that in a container, then doing `docker kill -sTERM` on said container.  The program prints `Got signal: SIGTERM`, then exits after the aforementioned timeout, as expected.  Behavior before this patch is that the program gets no notification (and thus no output) but still exits after the timeout.

Fixes golang#7479
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tianon committed Aug 14, 2019
1 parent 9195948 commit 9e05d63
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Showing 7 changed files with 43 additions and 14 deletions.
8 changes: 8 additions & 0 deletions src/os/signal/doc.go
Original file line number Diff line number Diff line change
Expand Up @@ -211,6 +211,14 @@ will cause os.Interrupt to be sent on the channel, and the program will
not exit. If Reset is called, or Stop is called on all channels passed
to Notify, then the default behavior will be restored.
Additionally, if Notify is called, and Windows sends CTRL_CLOSE_EVENT,
CTRL_LOGOFF_EVENT or CTRL_SHUTDOWN_EVENT to the process, Notify will
return syscall.SIGTERM. Unlike Control-C and Control-Break, Notify does
not change process behavior when either CTRL_CLOSE_EVENT,
CTRL_LOGOFF_EVENT or CTRL_SHUTDOWN_EVENT is received - the process will
still get terminated unless it exits. But receiving syscall.SIGTERM will
give the process an opportunity to clean up before termination.
Plan 9
On Plan 9, signals have type syscall.Note, which is a string. Calling
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10 changes: 7 additions & 3 deletions src/runtime/defs_windows.go
Original file line number Diff line number Diff line change
Expand Up @@ -41,9 +41,13 @@ const (
DUPLICATE_SAME_ACCESS = C.DUPLICATE_SAME_ACCESS
THREAD_PRIORITY_HIGHEST = C.THREAD_PRIORITY_HIGHEST

SIGINT = C.SIGINT
CTRL_C_EVENT = C.CTRL_C_EVENT
CTRL_BREAK_EVENT = C.CTRL_BREAK_EVENT
SIGINT = C.SIGINT
SIGTERM = C.SIGTERM
CTRL_C_EVENT = C.CTRL_C_EVENT
CTRL_BREAK_EVENT = C.CTRL_BREAK_EVENT
CTRL_CLOSE_EVENT = C.CTRL_CLOSE_EVENT
CTRL_LOGOFF_EVENT = C.CTRL_LOGOFF_EVENT
CTRL_SHUTDOWN_EVENT = C.CTRL_SHUTDOWN_EVENT

CONTEXT_CONTROL = C.CONTEXT_CONTROL
CONTEXT_FULL = C.CONTEXT_FULL
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10 changes: 7 additions & 3 deletions src/runtime/defs_windows_386.go
Original file line number Diff line number Diff line change
Expand Up @@ -15,9 +15,13 @@ const (
_DUPLICATE_SAME_ACCESS = 0x2
_THREAD_PRIORITY_HIGHEST = 0x2

_SIGINT = 0x2
_CTRL_C_EVENT = 0x0
_CTRL_BREAK_EVENT = 0x1
_SIGINT = 0x2
_SIGTERM = 0xF
_CTRL_C_EVENT = 0x0
_CTRL_BREAK_EVENT = 0x1
_CTRL_CLOSE_EVENT = 0x2
_CTRL_LOGOFF_EVENT = 0x5
_CTRL_SHUTDOWN_EVENT = 0x6

_CONTEXT_CONTROL = 0x10001
_CONTEXT_FULL = 0x10007
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10 changes: 7 additions & 3 deletions src/runtime/defs_windows_amd64.go
Original file line number Diff line number Diff line change
Expand Up @@ -15,9 +15,13 @@ const (
_DUPLICATE_SAME_ACCESS = 0x2
_THREAD_PRIORITY_HIGHEST = 0x2

_SIGINT = 0x2
_CTRL_C_EVENT = 0x0
_CTRL_BREAK_EVENT = 0x1
_SIGINT = 0x2
_SIGTERM = 0xF
_CTRL_C_EVENT = 0x0
_CTRL_BREAK_EVENT = 0x1
_CTRL_CLOSE_EVENT = 0x2
_CTRL_LOGOFF_EVENT = 0x5
_CTRL_SHUTDOWN_EVENT = 0x6

_CONTEXT_CONTROL = 0x100001
_CONTEXT_FULL = 0x10000b
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10 changes: 7 additions & 3 deletions src/runtime/defs_windows_arm.go
Original file line number Diff line number Diff line change
Expand Up @@ -16,9 +16,13 @@ const (
_DUPLICATE_SAME_ACCESS = 0x2
_THREAD_PRIORITY_HIGHEST = 0x2

_SIGINT = 0x2
_CTRL_C_EVENT = 0x0
_CTRL_BREAK_EVENT = 0x1
_SIGINT = 0x2
_SIGTERM = 0xF
_CTRL_C_EVENT = 0x0
_CTRL_BREAK_EVENT = 0x1
_CTRL_CLOSE_EVENT = 0x2
_CTRL_LOGOFF_EVENT = 0x5
_CTRL_SHUTDOWN_EVENT = 0x6

_CONTEXT_CONTROL = 0x10001
_CONTEXT_FULL = 0x10007
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2 changes: 2 additions & 0 deletions src/runtime/os_windows.go
Original file line number Diff line number Diff line change
Expand Up @@ -894,6 +894,8 @@ func ctrlhandler1(_type uint32) uint32 {
switch _type {
case _CTRL_C_EVENT, _CTRL_BREAK_EVENT:
s = _SIGINT
case _CTRL_CLOSE_EVENT, _CTRL_LOGOFF_EVENT, _CTRL_SHUTDOWN_EVENT:
s = _SIGTERM
default:
return 0
}
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7 changes: 5 additions & 2 deletions src/syscall/types_windows.go
Original file line number Diff line number Diff line change
Expand Up @@ -176,8 +176,11 @@ const (
FILE_MAP_READ = 0x04
FILE_MAP_EXECUTE = 0x20

CTRL_C_EVENT = 0
CTRL_BREAK_EVENT = 1
CTRL_C_EVENT = 0
CTRL_BREAK_EVENT = 1
CTRL_CLOSE_EVENT = 2
CTRL_LOGOFF_EVENT = 5
CTRL_SHUTDOWN_EVENT = 6
)

const (
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